Electric injection mechanism

ABSTRACT

The object of the present invention is to allow to perform easily the centering of the injection heating cylinder and the screw driver by a simple means even after the assembly, by providing an electric injection mechanism with a height adjustment means of the screw driver. A front plate provided with an injection heating cylinder 4 having a screw 3 installed inside at the front middle and a rear plate 2 provided with an electric motor 5 for injection-driving are rested on and fixed to the installation member 7. The front and rear plates 1, 2 are linked by means of a plurality of guide bars 6 installed right and left between the plates. The screw driver 10 is inserted into the guide bar 6 and disposed movably forward and backward between the plates. A driving means connected to the electric motor 5 and composed of a ball screw shaft 11 and a ball nut member 12 is installed over the screw driver 10 and the rear plate 2. A centering member 16 interposed between the installation means 7 for slidably supporting the screw driver 10 and, moreover, provided with a height adjustment means is installed at lower both sides of the screw driver 1.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention concerns an electric injection mechanismfor driving the screw injection by an electric motor.

[0003] 2. Detailed Description of the Prior Art

[0004] The electric injection mechanism having an electric motor such aservomotor or the like as driving source, and injection-driving a screwby converting rotation movement by the electric motor into linermovement by a ball screw shaft and a ball nut member, includes oneadopting a single ball screw shaft and one adopting a plurality of ballscrew shafts.

[0005] In any of these types, a screw driver is inserted movably forwardand backward into a guide bar between a pair of front and rear plates,and the ball screw shaft rotating by the electric motor engages with theball nut member installed in the screw driver. Further, the rear end ofa screw in an injection heading cylinder mounted at the front middle ofthe front plate is rotatably linked to the front middle of the screwdriver.

[0006] In such a configuration, if the injection heating cylinder andthe screw driver are decentered even slightly in the mounting, theinjection heating cylinder and the screw therein are also decenteredprovoking gnawing or break and, moreover, the parallelism with a guidebar supporting the screw driver goes wrong, increasing the slidingresistance against the movement of the screw driver, and inconveniencesof control or troubles or others appear easily by these causes.

[0007] The centers of the injection heating cylinder and screw driverare defined by the processing accuracy or the assembling accuracy ofrespective members composing an injection mechanism, and it is claimedthat it is extremely difficult to adjust the misalignment aftercompletion of the assembling. However, as it is pretended that themisalignment often appears in the height direction by the effect of theload, and the misalignment during the service is caused by theinflection of the guide bar due to the load of the screw driver, most ofproblems due to the misalignment shall be resolved, if the height of thescrew driver can be adjusted by any means, even after the assembling.

[0008] The present invention devised in consideration of the situationmentioned above has an object to provide a novel electric injectionmechanism allowing to adjust the height of the screw driver by anextremely simple means after the assembling, align easily the injectionheating cylinder and the screw driver easily, and prevent misalignmentduring the operation.

SUMMARY OF THE INVENTION

[0009] According to the object, the present invention is the one,comprising a front plate provided with an injection heating cylinderhaving a screw inside at the front middle, a rear plate provided with anelectric motor for injection-driving, an installation member affixingboth plates, a plurality of guide bars installed at the right and at theleft between the plates by linking with the pair of front and rearplates, a screw driver disposed movably forward and backward between theplates by inserting into the guide bars and a driving means comprised ofball screw shaft and ball nut member disposed over the screw driver andthe rear plate by connecting with the electric motor, wherein a memberfor centering the injection heating cylinder and screw driver, slidablysupporting the screw driver, being interposed between the installationmember, and having a height adjustment means, is installed at both sidesof the lower portion of the screw driver.

[0010] In addition, the driving means is the one, comprised of a pair ofball screw shafts rotatably juxtaposed over the front plate and rearplate, and a pair of the ball nut members at both sides of the screwdriver, installed in the screw driver and engaging respectively with theball screw shafts.

[0011] Further, the centering member is the one, comprised of a pair ofwedge-shape members overlapping alternately by forming the contactsurface respectively as the slant surface, both are linked relativelymovably by an adjustment screw, the one is affixed to the bottom face ofthe screw driver, while the other is put on the top face of theinstallation member.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012]FIG. 1. a side view showing a part of the electric injectionmechanism of the present invention by a section;

[0013]FIG. 2. section view along the line A-A of the same;

[0014]FIG. 3. a side view of essential parts of another embodiment;

[0015]FIG. 4. a side view of the electric injection mechanism of thepresent invention provided with a driving means by a pair of ball screwshaft wherein the electric motor is omitted;

[0016]FIG. 5. a section view along the line B-B of the same.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0017] In the drawing, 1 indicates a front plate and 2 a rear plate, thefront plate 1 is provided with an injection heating cylinder 4 having ascrew 3 for injection installed inside, rotatably and movably forwardand backward, at the front middle, and the rear plate 2 is provided withan electric motor 5 of injection-driving by a servomotor or the like.

[0018] The pair of front and rear plates 1, 2 are linked to four cornersby guide bars 6, 6, and at the same time, both sides of the lowerportion are respectively fixed onto both ends of a pair of right andleft installation members 7, for affixing on the top face of afoundation 9 of a machine base 8.

[0019]10 indicates a screw driver, disposed movably forward and backwardbetween the pair of front and rear plates 1, 2 and, the rear end of thescrew 3 is rotatably linked to the front middle thereof. Also, a ballnut member 12 engaged with a ball screw shaft 11 born rotatably by therear plate 2 is mounted integrally to the rear middle of the screwdriver.

[0020] Though not shown in the drawing, an electric motor and a screwrotation mechanism of weighing the material is mounted on the screwdriver 10.

[0021] A pulley 13 is attached to the outer end of the rear plate 2 ofthe ball screw shaft 11, and a timing belt 15 is wound around the pulley13 and a pulley 14 of the electric motor 5. Thereby, the ball screwshaft 11 is rotated by the electric motor 5, the rotational movement isconverted into a liner movement by the ball nut member 12, the screwdriver 10 drives forward with the screw, and resin weighed in the frontsection of the injection heating cylinder 4 is injected.

[0022]16 indicates an centering member of the injection heating cylinder4 and screw driver 10, comprised of a pair of wedge-shape membersoverlapping alternately by forming a contact surface respectively as aslant surface, and both of them are linked relatively movably by anadjustment screw 17 on the side.

[0023] One of the centering members 16 is affixed as upper member 16 ato the bottom face just under the guide bar of the screw driver 10,while the other is put as sliding lower member 16 b on the top face ofthe installation member 7, between both sides of the lower section ofthe screw driver 10 and installation member 7, and the height of thescrew driver 10 is changed together with a tie bar 6, by changing thedegree of their mutual overlapping by rotating the adjustment screw 17,whereby the injection heating cylinder 4 and screw driver 10 can bealigned.

[0024] During the attachment of the centering member 16, it ispreferable to put a sliding plate 18 on the top face, set the lowermember 16 b thereon, so that the forward and backward movement of thescrew driver 10 generates smoothly, and the height adjustment positionby the centering member 16 is maintained also during the operation, evenwhen both sides of its lower section is in a state being alwayssupported by the installation member 7.

[0025] Concerning also the attachment point of the centering member 16,though it is attached to two point at the front lower side of the screwdriver 10, in the embodiment of FIG. 1 and 2, it is preferable to attachalso to the rear section for performing the height adjustment andsupport of the screw driver 10 at front and rear four points, as shownin FIG. 3, according to the increase in size of the screw driver 10.

[0026] In the aforementioned embodiment, as the height of the screwdriver 10 can be adjusted together with the tie bar 6 even after theassembly, by attaching the centering member 16, the centering of theinjection heating cylinder 4 and the screw driver 10 can be performedeasily only by adjusting the height of the screw driver 10 through theindividual operation of right and left, or front and rear right and leftcentering members 16, 16, even in a case where such centering isrequired, from the processing accuracy or assembly state of theinjection mechanism.

[0027] Besides, in the one adopting wedge-shape upper and lower members16, 16 for the centering member 16, the structure is extremely simpleand the attachment can be completed simply, and even a delicatemisalignment can be rectified, as the height adjustment can be performedby changing the degree of overlapping of mutual slant faces through thescrew rotation.

[0028] Still further, as both sides of the screw driver 10 is in a stategrounded to the machine base side by the centering member 16, the screwdriver side load is shared by both of the guide bar 6 and the centeringmember 16, whereby, allowing to prevent an misalignment caused by theflexion due to the load of the guide bar 6.

[0029]FIG. 4 and FIG. 5 shown embodiments of the electric injectionmechanism provided with twin shaft type driving means. It should beappreciated that same parts as the embodiment shown in FIG. 1 to FIG. 3are indicated by the same symbol.

[0030] In this embodiment also, a pair of front and rear plates 1, 2 areaffixed to the machine base 8 by linking with guide bars 6, 6 at fourcorners, and the fixation is realized by resting and affixing the lowerboth sides on a disk-shape installation member 71 put on the top face ofthe foundation 9.

[0031] Besides, at both sides middle of the front and rear plates 1,2, apair of ball screw shafts 11, 11 are installed, being rotatablysupported in parallel with the guide bars 6, 6. The read end of the ballscrew shaft 6, 6 is connected on an electric motor for injection-driving(not shown).

[0032] A screw driver 10 is supported movably forward and backward byinserting into the guide bar 6, 6, and in the middle of right and leftboth side of the screw driver 10, a pair of ball nut members 12, 12moving with the screw driver 10 on the ball screw shaft, engaging withthe ball screw shaft 11 is installed inside.

[0033] A centering member 16 of the screw driver 10 is installed betweenthe front and rear both sides of the lower portion wherein the guide bar6, 6 of the screw driver 10 is inserted and the installation member 71.The centering member 16 is comprised of a pair of wedge-shape membersoverlapping alternately by forming a contact surface respectively as aslant surface, and both of them are linked relatively movably by anadjustment screw 17 on the side.

[0034] One of the centering members 16 is affixed as upper member 16 ato the bottom face inside the guide bar of the screw driver 10, whilethe other is rested as lower member 16 b on the top face at both sidesof the installation member 71, and the height of the screw driver 10 ischanged together with the tie bar 6, by changing the degree of theirmutual overlapping by rotating the adjustment screw 17, whereby theinjection heating cylinder 4 and screw driver 10 can be aligned.

[0035] In addition, during the attachment of the centering member 16, asliding plate 18 is put on the top face at both sides of theinstallation member 71, the lower member 16 b is rested thereon, so thata smooth sliding generates, even when both sides of the lower section ofthe screw driver 10 is in a state being always supported by theinstallation member 71.

[0036] As mentioned above, in the electric injection mechanism providedwith a twin type driving means also, the height of the screw driver 10after the assembly can be adjusted together with the tie bar 6, byattaching the centering member 16. Therefore, the centering can beperformed easily, even in a case where such centering is required, fromthe processing accuracy or assembly state of the injection mechanism,and the screw driver side load can be shared through the centeringmember 16, allowing to prevent the misalignment caused by the flexiondue to the load of the guide bar 6.

What is claimed is:
 1. An electric injection mechanism, comprising: afront plate provided with an injection heating cylinder having a screwinside at the front middle, a rear plate provided with an electric motorfor injection-driving, an installation member affixing both plates, aplurality of guide bars installed at the right and at the left betweenthe plates by linking with said pair of front and rear plates, a screwdriver disposed movably forward and backward between the plates byinserting into the guide bars, and a driving means comprised of ballscrew shaft and ball nut member disposed over the screw driver and therear plate by connecting with said electric motor, wherein: a centeringmember for centering said injection heating cylinder and screw driver,having a height adjustment means and slidably supporting the screwdriver by being interposed between said installation member and saidscrew driver is installed at both sides of the lower portion of saidscrew driver.
 2. The electric injection mechanism of claim 1, wherein:said driving means is comprised of a pair of ball screw shafts rotatablyjuxtaposed over said front plate and rear plate, and a pair of said ballnut members at both sides of the screw driver, installed in said screwdriver and engaging respectively with the ball screw shafts.
 3. Theelectric injection mechanism of claim 1, wherein: said centering memberis comprised of a pair of wedge-shape members overlapping alternately byforming a contact surface respectively as the slant surface, both arelinked relatively movably by an adjustment screw, the one is affixed toa bottom face of said screw driver, while the other is put on a top faceof said installation member.